The ContentHandler interface lets you receive the XML content.

For example:

class ListElements extends DefaultHandler {
   Map elements = new HashMap();
   public void startElement(String namespaceURI, String localName, String qName, Attributes atts) {
      if (namespaceURI==null) {
         elements.put(localName,Boolean.TRUE);
      } else {
         elements.put('{'+namespaceURI+'}'+localName,Boolean.TRUE);
      }
   }
}